Why do this on mobile?
A growing share of document and file workflows happen entirely on smartphones. You might receive a PDF on your phone, need to reduce its size before forwarding it, and want to add a password before sending it to a recipient. Doing this privately — without uploading the file to an external service — is now possible directly from a mobile browser, with no app installation required. For a full overview of private compression on mobile, see our guide on compressing files privately on iPhone and Android (minifiles.io/blog/apps-that-compress-files-privately-on-mobile-devices).
What MiniFiles does on mobile
MiniFiles provides two distinct operations on mobile: Compress — reduces the size of PNG, JPEG, JPG, WebP, GIF, and PDF files locally in the browser. Protect — applies AES-256 password protection to PDF files locally in the browser. Both operations run on the device. Files are never uploaded to any external server. Both features work in mobile browsers on iOS and Android.
How to compress files on mobile
- Open MiniFiles in your mobile browser. 2. Select the Compress tab. 3. Tap to select files (images or PDFs) from your device or cloud storage. 4. Files are compressed locally and immediately. 5. Use the quality slider to adjust if needed. 6. Download the compressed files. No upload. No account.
How to password-protect a PDF on mobile
- In MiniFiles, select the Protect tab. 2. Tap to select a PDF. 3. Enter a user password (required to open the file). 4. Optionally open Advanced Options to set an owner password (restricts printing, copying, editing). 5. Tap Protect. 6. Download the password-protected PDF. The protection engine runs locally on your phone — no upload.
Compress and protect in one operation
MiniFiles includes a 'Compress before protecting' toggle in the protection settings. Enabling this compresses the PDF first and then applies the password, all in a single local operation on your mobile device. This produces a smaller, password-protected PDF — useful before sending a large document by email or messaging app.
Which mobile browsers are supported
MiniFiles works in modern mobile browsers including: Safari on iOS (iPhone and iPad), Chrome on iOS and Android, Firefox on Android, Samsung Internet on Android, and other Chromium-based mobile browsers. No browser extension or plugin is required.
Privacy on mobile: what 100% private means
When MiniFiles says 100% private on mobile, it means: the compression and protection engines are downloaded to your mobile browser and run there; your files are read from device storage into browser memory, processed locally, and returned as a download; no file data is sent to any external server during compression or protection. This applies equally on iPhone, iPad, and Android devices.
Practical use cases on mobile
Compressing a photo before sending it via WhatsApp or Telegram. Reducing a PDF before attaching it to an email from your phone. Password-protecting a contract or confidential document before forwarding it. Compressing and protecting a PDF in one step before sharing via a file transfer app. All of these can be done locally on the device with MiniFiles.
Conclusion
MiniFiles provides a complete mobile workflow for private file compression and PDF protection — without installing an app, without uploading files, and without requiring a desktop. Open the browser, compress or protect, download the result. Works on iOS and Android.